Irrigation Engineering

51. If H and d are the water depth and drop in the bed level at a Sarda fall, the width B of the trapezoidal crest, is given by

1. B = 0.22 √(H + d)
2. B = 0.33 √(H + d)
3. B = 0.44 √(H + d)
4. B = 0.55 √(H + d)

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52. If L is total length of a canal in kilometres, P is total perimeter of its lining in metres and C is the cost of lining per square metre, the additional expenditure involved on lining, is

1. 100 PLC
2. PLC/1000
3. PL/1000C
4. PC/100L

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53. If straight sides of a triangular section of a lined canal with circular bottom of radius R, make an -section, is

1. R(θ + tan θ)
2. R(θ + cot θ)
3. R²(θ + tan θ)
4. R²(θ + cot θ)

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54. If the height of the hydraulic gradient line above the floor of thickness t is h and the specific gravity of the material of the floor is G, the minimum thickness t of the floor downstream of the crest-wall, is given by the equation

1. t = (h + 1)/(G + t)
2. t = (h - 1)/(G + t)
3. t = (h - 1)/(G - t)
4. t = (h + 1)/G

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55. If the irrigation efficiency is 80%, conveyance losses are 20% and the actual depth of watering is 16 cm, the depth of water required at the canal outlet, is

1. 10 cm
2. 15 cm
3. 20 cm
4. 25 cm

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56. If the optimum depth of kor watering for a crop is 15.12 cm, the outlet factor for the crop for four week period in hectares per cumec, is

1. 1000
2. 1200
3. 1400
4. 1600

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57. If the straight sides of a triangular section of a lined canal with circular bottom of radius D, make th horizontal, the hydraulic mean depth is

1. D
2. D/2
3. D/3
4. D/5

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58. If the straight sides of a triangular section of a lined canal with circular bottom of radius R, make an angle θ with horizontal, the perimeter of the canal is

1. R(θ + tan θ)
2. 2R(θ + tan θ)
3. R(θ + cos θ)
4. 2R(θ + cos θ)

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59. If V0 is the critical velocity of a channel, its silt transporting power, according to Kennedy, is proportional to

1. V₀^1/2
2. V₀^3/2
3. V₀^5/2
4. V₀^7/2

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60. If water table is comparatively high, the irrigation canal becomes useless, due to

1. Large amount of seepage
2. Water logging of the cultivated areas
3. Uncertain water demand
4. All the above

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